October 16, 2016

It would be easy to diverge from this general overview into a detailed examination of the physics. This is because Epicurus seems to have been largely right. We now believe, as he did, that the universe is made of atoms, and if we do not now talk about motion, we do talk about energy and force. His physics are an astonishing achievement.

Of course, he was often wrong. He denigrated mathematics. He seems to have believed that the sun and moon were about the same size as they appear to us. Then there is an apparent defect in his conception of the atomic movements. Does the universe exist by accident? Or are their laws of nature beyond the existence and movement of the atoms? The first is not impossible. An infinite number of atoms in an infinite void over infinite time will, every so often, come together in an apparently stable universe. They may also hold together, moving in clusters in ways that suggest regularity. But this chance combination might be dissolved at any moment — though, given every sort of infinity, some of these universes will continue for long periods.

If Epicurus had this first in view, what point in trying to explain present phenomena in terms of cause and effect? Causality only makes sense on the assumption that the future will be like the past. If he had the second in mind, it is worth asking what he thought to he nature of these laws? Might they not, for example, have had an Author? Since Newton, we have contented ourselves with trying to uncover regularities of motion and not going beyond these. But the Greeks had a much stronger teleological sense.

Perhaps these matters were not discussed. Perhaps they were discussed, but we have no record of them in the surviving discussions. Or perhaps they have survived, but I have overlooked them. But it does seem to me that Epicurean physics do not fully discuss the nature of the laws that they assume.

On the other hand, let me quote two passages from his surviving writings:

Moreover, there is an infinite number of worlds, some like this world, others unlike it. For the atoms being infinite in number… are borne ever further in their course. For the atoms out of which a world might arise, or by which a world might arise, or by which a world might be formed, have not all be expended on one world or a finite number of worlds, whether like or unlike this one. Hence there will be nothing to hinder and infinity of worlds….

And further, we must not suppose that the worlds have necessarily one and the same shape. For nobody can prove that in one sort of world there might not be contained, whereas in another sort of world there could not possibly be, the seeds out of which animals and plants arise and the rest of the things we see.

What we have here is the admission that there may, in the infinite universe, be other worlds like our own, and these may contain sentient beings like ourselves. And there may be worlds inconceivably unlike our own. And there is the claim that living beings arise and develop according to natural laws. Epicurus would not have been surprised either by modern physics or by Darwinism. […]

However, while the similarities between Epicurean physics and modern science are striking, there is one profound difference. For us, the purpose of science is to give us an understanding of the world that brings with it the ability to control the world and remake it for our own convenience. This is our desire, and this has been our achievement because we have fully developed methods of observation and experiment. The Greeks had limited means of observation — no microscopes or telescopes, nor even accurate clocks. Nor had they much conception of experiment.

Moreover, scientific progress was neither conceived by Epicurus nor regarded as desirable. He says very emphatically:

If we had never been troubled by celestial and atmospheric phenomena, nor by fears about death, nor by our ignorance of the limits of pains and desires, we should have had no need of natural science.

He says again:

…[R]emember that, like everything else, knowledge of celestial phenomena, whether taken along with other things or in isolation, has no other end in view than peace of mind and firm convictions.